[SR-Users] Unable to establish TCP connection with Kamailio

Hello, I'm running Kamailio Version 5.3.2 on Ubuntu 20.04. Here my build information: version: kamailio 5.3.2 (x86_64/linux) flags: USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES, TLS_PTHREAD_MUTEX_SHARED ADAPTIVE_WAIT_LOOPS 1024, MAX_RECV_BUFFER_SIZE 262144, MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB poll method support: poll, epoll_lt, epoll_et, sigio_rt, select. id: unknown compiled with gcc 9.2.1 I have the following configuration set in my kamalio.cfg file: ##!define WITH_MYSQL ##!define WITH_AUTH ##!define WITH_USRLOCDB ##!define WITH_TLS ##!define WITH_HOMER ##!define WITH_WEBSOCKETS ##!define WITH_ANTIFLOOD ##!define WITH_IPV6 ##!define WITH_BRIDGE_ON_FAIL ##!define WITH_LOCALHOST_WS ##!define WITH_LOCALHOST_SIP #!substdef "!MY_SIP_PORT!5060!g" #!substdef "!MY_SIPS_PORT!5061!g" #!substdef "!MY_WS_PORT!8088!g" #!substdef "!MY_WSS_PORT!8089!g" #!substdef "!MY_LOG_FACILITY!LOG_DAEMON!g" #!substdef "!MY_IP4_ADDR!172.16.0.57!g" #!substdef "!IP4_LOCALHOST!127.0.0.1!g" #!substdef "!MY_WS4_ADDR!tcp:MY_IP4_ADDR:MY_WS_PORT!g" #!substdef "!MY_WSS4_ADDR!tls:MY_IP4_ADDR:MY_WSS_PORT!g" #!substdef "!LOCALHOST_WS4_ADDR!tcp:IP4_LOCALHOST:MY_WS_PORT!g" #!substdef "!LOCALHOST_WSS4_ADDR!tls:IP4_LOCALHOST:MY_WSS_PORT!g" #!ifdef WITH_IPV6 #!substdef "!MY_IP6_ADDR![fe80::d6e4:2f5f:e5b7:7dff]!g" #!substdef "!IP6_LOCALHOST![::1]!g" #!substdef "!MY_WS6_ADDR!tcp:MY_IP6_ADDR:MY_WS_PORT!g" #!substdef "!MY_WSS6_ADDR!tls:MY_IP6_ADDR:MY_WSS_PORT!g" #!substdef "!LOCALHOST_WS6_ADDR!tcp:IP6_LOCALHOST:MY_WS_PORT!g" #!substdef "!LOCALHOST_WSS6_ADDR!tls:IP6_LOCALHOST:MY_WSS_PORT!g" #!endif #!substdef "!MY_DOMAIN!rtpengine.kombea.io!g" debug=10 // debug level (cmd line: -dddddddddd) children=4 #fork=yes force_rport=yes // Add recieved port to VIA #log_stderror=no // (cmd line: -E) // Uncomment these lines to enter debugging mode fork=no log_stderror=yes check_via=no // (cmd. line: -v) dns=no // (cmd. line: -r) rev_dns=no // (cmd. line: -R) log_facility=MY_LOG_FACILITY // Define the listening ports and addresses port=MY_SIP_PORT tls_port_no=MY_SIPS_PORT // Define TCP parameters tcp_children=4 tcp_no_connect=no tcp_rd_buf_size=16384 tcp_max_connections=2048 tcp_connection_lifetime=3605 disable_tcp=no #!ifdef WITH_TLS enable_tls=yes #!endif listen=MY_IP4_ADDR #!ifdef WITH_LOCALHOST_SIP listen=IP4_LOCALHOST #!endif #!ifdef WITH_IPV6 listen=MY_IP6_ADDR #!ifdef WITH_LOCALHOST_SIP listen=IP6_LOCALHOST #!endif #!endif #!ifdef WITH_WEBSOCKETS listen=MY_WS4_ADDR #!ifdef WITH_LOCALHOST_WS listen=LOCALHOST_WS4_ADDR #!endif #!ifdef WITH_IPV6 listen=MY_WS6_ADDR #!ifdef WITH_LOCALHOST_WS listen=LOCALHOST_WS6_ADDR #!endif #!endif #!ifdef WITH_TLS listen=MY_WSS4_ADDR #!ifdef WITH_LOCALHOST_WS listen=LOCALHOST_WSS4_ADDR #!endif #!ifdef WITH_IPV6 listen=MY_WSS6_ADDR #!ifdef WITH_LOCALHOST_WS listen=LOCALHOST_WSS6_ADDR #!endif #!endif #!endif #!endif force_rport=yes // Add received port to VIA loadmodule "pv.so" // Pseudo-Variable support loadmodule "xlog.so" // Formatted logging support loadmodule "sl.so" // Stateless request handling loadmodule "siputils.so" // SIP utility helpers loadmodule "sanity.so" // Sanity check loadmodule "maxfwd.so" // Support for Max-Forward header loadmodule "textops.so" // Text operations on SIP messages loadmodule "textopsx.so" // Extended Text operations on SIP messages loadmodule "sdpops.so" // SDP operations loadmodule "nathelper.so" // NAT traversal helpers loadmodule "rr.so" // Record Route handling loadmodule "outbound.so" // Outbound support loadmodule "path.so" // Path handling #!ifdef WITH_TLS loadmodule "tls.so" // TLS Support #!endif #!ifdef WITH_WEBSOCKETS loadmodule "xhttp.so" // XHTTP support loadmodule "websocket.so" // WebSocket support #!endif loadmodule "rtpengine.so" // RTPEngine control #!ifdef WITH_DEBUG loadmodule "debugger.so" #!endif When I start Kamailio, I see the following in the output to stderr: Listening on udp: 172.16.0.57:5060 tcp: 172.16.0.57:5060 Aliases: tcp: VRTPENGINE:5060 udp: VRTPENGINE:5060 WARNING: no fork mode 0(6299) INFO: <core> [core/tcp_main.c:5042]: init_tcp(): using epoll_lt as the io watch method (auto detected) Here's the problem: When I connect via UDP, everything works fine. I can connect and see all SIP traffic. However, if I try to connect via TCP, I see the initial SYN packet in attempting to establish a connection. Kamailio responds with an [RST,ACK] message and the TCP connection is never established. No further TCP traffic is sent. Any ideas on what I'm doing wrong? Peter H. Manley, Ph.D. Chief Software Architect KomBea Corporation 3400 North Ashton Blvd, Suite 470<https://urldefense.proofpoint.com/v2/url?u=https-3A__maps.google.com… Lehi, Utah 84043<https://urldefense.proofpoint.com/v2/url?u=https-3A__maps.google.c… www.kombea.com<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.k… Office:+1.801.610.5808 Mobile +1.801.243.7773